XIR242416 Exterior view of the Aula Palatina, built c.310 (photo) by Roman, (4th century AD); Trier, Germany; (add.info.: basilican tribunal of the Roman palace; built by Emperor Constantine on the site of a ruined c02nd palace; became electoral schloss in c17th; largest surviving single room structure from Roman times; 27m wide, 33m high and 67m long;); out of copyright.